Fatty and amino acid profile of mealworm larvae (Tenebrio molitor L.)

Abstract

The yellow mealworm (Tenebrio molitor L., Coleoptera: Tenebrionidae) is an edible insect, distributed worldwide and a convenient candidate for industrial-scale production. Mealworms could be commercially used for the substitution of conventional protein sources. In our previous study, it was found that T. molitor larvae predominantly contained crude protein (55.83%) and crude fat (25.19%), as well as low content of nitrogen-free extract (based on dry weight). Mealworm specimens were maintained in an incubator under controlled conditions in plastic containers. Insects were sieved and put into the container with boiling water and cooked for 180 seconds. Moisture content was determined as weight loss after drying of larvae. Amino acids were determined on an Agilent Technologies 1260 series HPLC system. Fatty acid composition was determined on a Thermo Scientific TRACE 1300 gas chromatograph equipped with a flame ionization detector using TR-FAME column. The results showed that the content of unsaturated fatty acid is very high, i.e. oleic acid (C18:1) formed the major lipid component in 40.83%, which was followed by linoleic acid (C18:2, omega-6 fatty acid) with 29.80% and linolenic acid (C18:3) with 1.08%. The essential amino acids are highly represented in the samples (in % dry matter). This primarily refers to isoleucine (4.12), tyrosine (3.86), phenylalanine (3.06), leucine (2.96), lysine (2.67) and methionine (1.76). The differences in essential fatty and amino acid content between our results and discussed literature data, could be the consequence of different substrates used for rearing of insects. After everything stated above, the biological value of T. molitor larvae proves that it could be suitable as animal feed.